1. Technical Field
This invention relates generally to the field of fluid flow measurement and especially to instruments for measuring and indicating the direction and speed of the wind.
2. Background Information
Wind measurements have been made for many years for numerous applications. Typically two separate instruments have been used to measure wind direction and wind speed. The relatively simple weather vane is commonly used to indicate wind direction while more complex devices such as a cup anemometer are employed to measure wind speed.
Some instruments, such as the propeller anemometer, have previously been developed to indicate both wind speed and direction. However, such instruments, generally exhibit a relatively slow response time, are complicated to fabricate, and are not readily adaptable to either provide a discernable visual indication of wind velocity or to measure very high wind speeds.
Heretofore, a single, simple instrument capable of simultaneously measuring both variable wind speed and variable direction, over an extended range, with high sensitivity, and in a predictable, accurate fashion has been unavailable. Further an anemometer which indicates direction as well as wind speed and operates, through inertial overshoot, in an oscillatory mode, at a frequency which is linearly proportional to wind speed has not been known.
U.S. Pat. No. 3,273,389 to C. C. Waugh describes an oscillating vane flow meter. However, this device is limited to measuring the rate of unidirectional flow of a fluid in a conduit, is of complex construction and requires an upstream vane or fin to induce oscillation.
A need thus persists for an instrument that is capable of measuring both the speed and direction of an unrestricted fluid flow, which is simple in design, easy to manufacture, linear over a large operating range, readily scaled up or down in size, and particularly well suited for anemometry.